1. Field of the Invention
The present invention relates to an apparatus for stacking cartridge shell plates of photographic film cartridges before assembling the photographic film cartridges.
2. Description of the Related Art
ISO 135-type photographic film cartridges are one of the most popular types of photographic film cartridges in use today. The 135-type film cartridge is constituted of a resin spool, a 35 mm filmstrip coiled around the spool, and a metal housing in which the spool and the filmstrip are contained. The housing is constituted of a cartridge shell plate bent into a cylindrical tube and a pair of caps fitted on the ends of the tube. Also a pair of light-trapping pieces or plush ribbons are stuck on the shell plate to prevent entrance of light through a film passage mouth of the housing which is formed by the ends of the shell plate that extend in the axial direction of the tube.
To produce such a film cartridge, the shell plates of the housing are blanked out of a metal plate and are bent into a U-shape. The plush ribbons are stuck onto the inside surface of the U-shaped blank or shell plate. Then, the shell plate is rounded into the cylindrical tube, into which the film roll wounded on the spool is inserted. Thereafter, the caps are attached to the tube to complete the assembly of the film cartridge.
Because there is a difference in speed between the plush sticking process and the cartridge assembly process, the shell plates to which the plush ribbons are stuck are temporarily stacked on a tray or the like. An automatic photographic film cartridge assembling apparatus having an automatic stacking system for the U-shaped shell plates is disclosed in Japanese Laid-open Patent Applications Nos. 3-290654 and 3-290657.
In the known shell plate stacking system, the cartridge shell plate is carried in the horizontal state with the plush ribbons stuck on the upside surface thereof, and is picked up by a magnet pulley. Then the cartridge shell plate is carried in the standing attitude on a belt conveyer having magnets disposed in the lower portion thereof. A stopper is disposed along the belt conveyer to dam up the cartridge shell plates and gather the same into a pile. When a predetermined amount of cartridge shell plates are thus accumulated, a robot hand removes the pile of the cartridge shell plates from the belt conveyer.
However, because the above-described known apparatus carries the cartridge shell plates in the standing attitude, the cartridge shell plates are unstable and may often fall over on the belt conveyer. If a cartridge shell plate falls over, it is necessary to stop the belt conveyer and put the cartridge shell plate in order. Also, because the robot hand does not pick up the cartridge shell plates from the belt conveyer until the pile of the cartridge shell plates reaches the predetermined amount, if no further cartridge shell plate is fed to the belt conveyer for, for example, during changing the type or design of film cartridge, the cartridge shell plates remaining on the belt conveyer must be manually transferred to the tray. Therefore, the efficiency of operation is unsatisfactory.
Moreover, because successive transportation of the cartridge shell plates in the standing attitude does not permit inspection of the outer surfaces of the cartridge shell plates, it is impossible to prevent the piling of a cartridge shell plate having a defective outer surface together with non-defective cartridge shell plates.